1. Field of the Invention
The present invention relates to an input device for operating an in-vehicle apparatus.
2. Description of Related Art
Modern vehicles are equipped with in-vehicle apparatuses, such as a navigation apparatus, an air conditioner, an audio apparatus and the like. There is known a system that has a display part (e.g., Liquid Crystal Display part) and an input part spaced apart from each other. Using the system, a user can operate the in-vehicle apparatus by manipulating the input part and by pointing an item on a window displayed on a display screen of the display part.
Regarding the above type of systems, in order to minimize movement of viewpoint of a driver, it may be preferable to place the display screen in front of the driver and as far as possible from the driver. Further, it is may be preferable to place the input part within a driver arm's reach, and preferable that a driver be not required to take a look at the input part to manipulate the input part.
The above type of systems frequently employs the following operational manners: a user manipulates the input part to move a cursor, which indicates a pointed point on the window; the cursor is moved onto an icon, which represents an instruction to the in-vehicle apparatus; and the icon is selected to issue the instruction. According to the above operational manners, however, it takes time and effort to move the cursor to a target position. Thus, the above manners can increase a time for a driver to gaze the window.
JP-A-2006-29917 discloses the following system. A selectable item such as an icon is displayed on a window of a display means. A user can select the selectable item by manipulating a touch-sensitive panel spaced apart from the display means. When a vehicle is traveling, an input operation is based on absolute positional data, which indicates absolute positions on the touch-sensitive panel. When a vehicle is making a stop, an input operation is based on relative positional data, which indicates relative positions on the touch-sensitive panel. An input operation based on absolute positions is also referred to herein as an absolute input. An input operation based on relative positions is also referred to herein as a relative input. JP-A-2006-29917 argues that it is possible to improve operability by switching an input manner between an absolute input manner and a relative input manner depending on whether a vehicle is traveling or making a stop.
There is, however, a remarkable difference in operational feeling between the known absolute input manner and the known relative input manner. When an input part employs an input manner as a mixture of the absolute and relative inputs, or when an input part switches the input manner between the absolute input manner and the relative input manner, it may be difficult for a user in some cases to catch whether the present input is involved in the absolute input manner or the relative input manner. In such a case, a user may be confused or may have discomfort feeling.